US5055114AExpiredUtility
Semipermeable membranes based on specified tetrabromobisphenol type polyesters

Assignee: UNION CARBIDE IND GASES TECHPriority: Dec 27, 1988Filed: Dec 6, 1989Granted: Oct 8, 1991
Est. expiryDec 27, 2008(expired)· nominal 20-yr term from priority
Inventors:James H. Kawakami Natarajan Muruganandam George L. Brode
B01D 71/48C08G 63/6826
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Claims
Abstract

Permeable membranes comprised predominantly of specifically defined tetrabromobisphenols and aromatic dicarboxylic acids. The invention also pertains to the novel permeation processes for recovery of an oxygen/nitrogen or carbon dioxide/methane component form a mixture of said component with other components.
Claims

exact text as granted — not AI-modified
What is claimed is: 
     
       1. A gas separation membrane comprising a thin layer consisting predominantly of a polyester or copolyester derived essentially from the reaction of an aromatic dicarboxylic acid or derivative thereof and greater than 50 mole percent of a tetrabromobisphenol of the general formula: ##STR9## wherein R&#39; is ##STR10## or divalent cyclododecyl and wherein said aromatic dicarboxylic acid or derivative thereof comprises (1) (a) 80 mole percent or more of isophthalic acid or its dichloride and/or 4-bromoisophthalic acid or its dichloride and (b) 20 mole percent or less of terephthalic acid or its dichloride and/or 2-bromoterephthalic acid or its dichloride as the dicarboxylic acid compound, or (2) (a) 30 mole percent or less of isophthaloyl dichloride and/or 4-bromoisophthalic acid or its dichloride and (b) 70 mole percent or more of terephthalic acid or its dichloride and/or 2-bromoterephthalic acid or is dichloride; said membrane having a combination of high selectivity and high permeation rate values for O 2  /N 2  and CO 2  /CH 4  separations. 
     
     
       2. A gas separation membranes as claimed in claim 1 derived essentially from the reaction of an aromatic acid or derivative thereof and a mixture of diols comprising greater than 50 mole percent of said tetrabromobisphenol (I) and less than 50 mole percent of a bisphenol of the general formula: ##STR11## wherein R&#34; is methyl or chlorine. 
     
     
       3. A gas separation membrane as claimed in claim 2 wherein said tetrabromobisphenol (I) comprises at least about 80 mole percent of the mixture of diols. 
     
     
       4. A gas separation membrane as claimed in claim 2 wherein said polyester based on aromatic dicarboxylic acid esters comprises a mixture of said bisphenols of said general formulas (I) and (II) wherein (I) is 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dibromophenol] and it is present at a concentration of 50 mole percent or greater in the copolyester. 
     
     
       5. A gas separation membrane as claimed in claim 4 wherein the bisphenols are a mixture of 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis [2,6-dibromophenol] and 4,4&#39;-[2,2,2,-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dimethylphenol]. 
     
     
       6. A gas separation membrane as claimed in claim 4 wherein the bisphenols are a mixture of 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dibromophenol] and 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dichlorophenol]. 
     
     
       7. A gas separation membrane as claimed in claim 1 wherein said tetrabromobisphenol (I) comprises 100 mole percent of the bisphenol diols. 
     
     
       8. A gas separation membrane as claimed in claim 1 wherein said combination for oxygen and nitrogen shows a selectivity of at least about 5.6 to about 7.2 and a permeation of at least about 4.7 to about 11.8 Barrers at ambient temperature and/or said combination for carbon dioxide and methane shows a selectivity of at least 30 and a permeation of at least about 15 Barrers at ambient temperature. 
     
     
       9. A gas separation membrane as claimed in claim 8 wherein the bisphenols are a mixture of 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dibromophenol] and 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclododecane. 
     
     
       10. A gas separation membrane as claimed in claim 1 wherein said polyester comprises 100 mole percent isophthalate for membranes based on 4,4&#39;-[2,2,2-trifluoromethy)ethylidene]bis[2,6-dibromophenol] for oxygen/nitrogen separations. 
     
     
       11. A gas separation membrane as claimed in claim 1 wherein said polyester comprises at least 70 mole percent terephthalate and not more than 30 mole percent isophthalate for membranes based on 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dibromophenol] for carbon dioxide/methane separations. 
     
     
       12. A gas separation membrane as claimed in claim 1, wherein said polyester comprises at least 70 mole percent 2-bromoterephthalate and not more than 30 mole percent 4-bromoterephthalate for membranes based on 4,4&#39;[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] bis[2,6-dibromophenol] for carbon dioxide/methane separations. 
     
     
       13. A gas separation membrane as claimed in claim 1 wherein said polyester comprises at least 75 mole percent 2-bromoterephthalates and not more than 25 mole percent 4-bromoterephthalate based on 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dibromophenol] for carbon dioxide/methane separations. 
     
     
       14. A gas separation membrane as claimed in claim 1 wherein said polyester comprises at least 80 mole percent isophthalate and not more than 20 mole percent of terephthalate for membranes based on 1,1- bis(3,5-dibromo-4-hydroxyphenol) cyclododecane for oxygen/nitrogen separations. 
     
     
       15. A gas separation membrane as claimed in claim 1 wherein said polyester comprises at least 70 mole percent terephthalate and not more than 30 mole percent of isophthalate for membranes based on 1,1- bis(3,5-dibromo-4-hydroxyphenyl) cyclododecane for carbon dioxide/methane separations. 
     
     
       16. A gas separation membrane as claimed in claim 1 wherein said tetrabromobisphenol of general formula (I) is 1,1-bis (3,5-dibromo-4-hydroxyphenyl) cyclododecane. 
     
     
       17. A gas separation membrane as claimed in claim 16 wherein said tetrabromobisphenols are a mixture of 1,1-bis (3,5-dibromo-4-hydroxyphenyl) cyclododecane and 4,4&#39;-bis (3,5-dimethyl-4-hydroxyphenyl) cyclododecane. 
     
     
       18. A gas separation membrane as claimed in claim 16 wherein said tetrabromobisphenol are a mixture of 1,1-bis (3,5-dibromo-4-hydroxyphenyl) cyclododecane and 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl) ehtylidene] bis [2,6-dichlorophenol]. 
     
     
       19. A gas separation membrane as claimed in claim 1 wherein said tetrabromobisphenol of general formula (I) is a mixture of 1,1-bis (3,5-dibromo-4-hydroxyphenyl) cyclododecane and 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis [2,6-dimethylphenol]. 
     
     
       20. A polyester gas separation membrane as claimed in claim 1 wherein the predominant recurring unit of said polyester has the structural formula: ##STR12## wherein R&#39; is as defined in claim 1, R&#39;&#34; is hydrogen or bromine and x is an integer having a value of at least about 20. 
     
     
       21. A gas separation membrane as claimed in claim 1 wherein said polyester comprises at least 80 mole percent isophthalate and not more than about 20 mole percent terephthalate for membranes based on 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis [2,6-dibromophenol] for oxygen/nitrogen separations. 
     
     
       22. A gas separation membrane as claimed in claim 1 wherein said polyester comprises 75 mole percent terephthalate and 25 mole percent isophthalate for membranes based ion 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dibromo phenol] for carbon dioxide/methane separations. 
     
     
       23. A gas separation membrane as claimed in claim 1 wherein said polyester comprises 100 mole percent 4-bromoisophthalate based on 4,4&#39;-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[2,6-dibromo phenol] for oxygen/nitrogen separations. 
     
     
       24. A process for separating a component from an O 2  /N or CO 2  /CH 4  gas mixture containing said component which comprises contacting said gas mixture with one side of a gas separation membrane comprising a thin layer consisting predominantly of a polyester or copolyester derived from the reaction of an aromatic dicarboxylic acid or derivative thereof and greater than 50 mole percent of a tetrabromobisphenol of the general formula: ##STR13## wherein R&#39; is ##STR14## or divalent cyclododecyl and wherein said aromatic dicarboxylic acid or derivative thereof comprises (1) (a) 80 mole percent or more of isophthalic acid or its dichloride and/or 4-bromoisophthalic acid or its dichloride and (b) 20 mole percent or less of terephthalic acid or its dichloride and/or 2-bromoterephthalic acid or its dichloride as the dicarboxylic acid compound, or (2) (a) 30 mole percent or less of isophthaloyl dichloride and/or 4-homoisophthalic acid or its dichloride and (b) 70 mole percent or more of terephthalic acid or its dichloride and/or 2-bromoterephthalic acid or is dichloride; said membrane having a combination of high selectivity and high permeation rate values, while maintaining a pressure differential across the two sides of the membrane and removing the permeated component from the other side of the membrane. 
     
     
       25. A process as claimed in claim 24, wherein said polyester or copolyester is derived essentially from an aromatic acid or derivative thereof and a mixture of diols comprising greater than 50 mole percent of said tetrabromobisphenol (I) and less than 50 mole percent of a bisphenol of the general formula: ##STR15## wherein R&#34; is methyl or chlorine. 
     
     
       26. A process as claimed in claim 24, wherein said tetrabromobisphenol (I) comprises at least about 80 mole percent of the mixture of diols. 
     
     
       27. A process as claimed in claim 23 wherein said tetrabromobisphenol (I) comprises 100 mole percent of the bisphenol diols. 
     
     
       28. A process as claimed in claim 23 wherein said gas mixture comprises oxygen and nitrogen. 
     
     
       29. A process as claimed in claim 27 wherein R&#39; of the tetrabromobisphenol (I) is ##STR16## 
     
     
       30. A process as claimed in claim 23 wherein said gas mixture comprises air. 
     
     
       31. A process as claimed in claim 23 wherein said gas mixture is a mixture comprising carbon dioxide and methane. 
     
     
       32. A process as claimed in claim 29 wherein R&#39; of the tetrabromobisphenol (I) is ##STR17## 
     
     
       33. A process as claimed in claim 23 wherein R&#39;of the tetrabromobisphenol (I) is ##STR18## 
     
     
       34. A process as claimed in claim 23 wherein the predominent recurring unit of said polyester has the structural formula: ##STR19## wherein R&#39; is as defined in claim 13, R&#39;&#34; is hydrogen or bromine and x is an integer having a value of at least about 20.
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